<?php

namespace WConvert\Destination;

use WConvert\Lead\Lead;

defined('ABSPATH') || exit;

/**
 * **What is being pushed** — the canonical values, and whether there is a
 * [[Lead]] row behind them.
 *
 * ========================================================================
 * A TEST SEND NEVER WRITES A LEAD, AND THIS IS WHAT MAKES THAT POSSIBLE.
 * ========================================================================
 * {@see DestinationType::push()} took a `Lead`, so every push was keyed by a
 * row in `wconvert_leads`. A merchant proving their Mailchimp key works would
 * then have had to write one — and a [[Lead]] has **exactly one origin**, a
 * visitor submitting a form on a page WConvert served (ADR 0031). A test Lead
 * carries a [[Consent Record]] nobody was ever shown, which is manufactured
 * evidence rather than a shortcut.
 *
 * So the thing a Destination is handed is the VALUES, and where they came from
 * is a separate fact. A capture supplies {@see self::of()}; a merchant pressing
 * *Send a test* supplies {@see self::test()}. Both reach one `push()`.
 *
 * **`isTest` is on the subject rather than on {@see PushContext}**, because it
 * is a property of what is being sent and not of how the Destination is
 * configured. The Destination is the same Destination either way; only the
 * provenance of the payload differs.
 *
 * A type is not obliged to read it. Every v1 type pushes a test exactly as it
 * pushes a capture, which is what makes the test worth anything — a code path
 * that behaves differently under test proves the code path, not the
 * integration. It is here so a type that genuinely must say so (a subject line,
 * a vendor's own test endpoint) can, without the caller inventing a second
 * method.
 *
 * @since 0.1.0
 */
final class PushSubject
{
    /**
     * @param array<string, string> $values Canonical keys, empties already dropped.
     */
    private function __construct(
        public readonly array $values,
        public readonly bool $isTest,
        /** @var array<string, string|true> Provider field id => accepted text or selected interest. */
        public readonly array $mapped = [],
        /** The accepted submission purpose; an email address alone is not marketing consent. */
        public readonly string $purpose = 'request',
        /**
         * One delivery of one submission to one Destination: the same on every
         * retry, different for each submission and each route. A receiver that
         * cannot be upserted into dedupes on it (ADR 0148).
         */
        public readonly string $deliveryId = '',
        /**
         * The submission as a whole, for a type that forwards it rather than
         * mapping it — {@see PushDetails}. Every other type ignores it.
         *
         * @var array<string, mixed>
         */
        public readonly array $details = [],
    ) {
    }

    /**
     * One captured [[Lead]], as the thing a Destination receives.
     *
     * `$lead` is the frozen snapshot of one submission. `$whole` is the Lead it
     * belongs to, which is what lets the details of a journey's second step
     * carry its first.
     */
    public static function of(Lead $lead, string $destinationId = '', string $submissionId = 'primary', ?Lead $whole = null): self
    {
        $mapping = $lead->capture['field_mappings'][$destinationId] ?? [];
        $mapped = [];
        if (is_array($mapping)) {
            foreach ($mapping as $source => $target) {
                if (!is_string($target) || !preg_match('/^[A-Za-z][A-Za-z0-9_]{0,31}$/D', $target)) continue;
                $value = null;
                if (is_string($source) && str_starts_with($source, 'choice:')) {
                    [, $question, $choice] = array_pad(explode(':', $source, 3), 3, '');
                    foreach ($lead->questionAnswers as $answer) {
                        if (($answer['id'] ?? null) !== $question || ($answer['type'] ?? '') !== 'multi') continue;
                        // Only selected choices add interests. Skipped or deselected choices never clear them.
                        if (in_array($choice, $answer['values'] ?? [], true)) $value = true;
                        break;
                    }
                } elseif (is_string($source) && str_starts_with($source, 'field:')) {
                    $key = substr($source, 6);
                    if (in_array($key, ['interest', 'message'], true)) $value = $lead->fields[$key] ?? null;
                } else {
                    foreach ($lead->questionAnswers as $answer) {
                        if (($answer['id'] ?? null) !== $source) continue;
                        $parts = ($answer['type'] ?? '') === 'text' ? ($answer['values'] ?? []) : ($answer['labels'] ?? []);
                        $value = is_array($parts) ? implode('; ', array_filter($parts, 'is_string')) : null;
                        break;
                    }
                }
                if ($value === true || (is_string($value) && trim($value) !== '')) $mapped[$target] = $value;
            }
        }
        return new self(CanonicalFields::of($lead), false, $mapped,
            is_string($lead->capture['purpose'] ?? null) ? $lead->capture['purpose'] : 'request',
            'msg_' . substr(hash('sha256', $lead->id . '|' . $submissionId . '|' . $destinationId), 0, 32),
            PushDetails::of($whole ?? $lead, $submissionId));
    }

    /**
     * A merchant's own address, with no row behind it.
     *
     * The values are put through the same {@see CanonicalFields} filter a Lead
     * is, so a test cannot reach a Destination carrying a key the vocabulary
     * does not have — which is the one way a test send could otherwise exercise
     * a path a capture never takes.
     *
     * Its details are a full sample — every key filled — so a receiver that
     * learns its fields from the first payload it sees (Zapier, Make) sees all
     * of them. A campaign editor passes that campaign's own questions.
     *
     * @param array<string, mixed> $values
     * @param array<string, string|true> $mapped
     * @param array<string, array{question: string, answer: string|list<string>}>|null $answers
     */
    public static function test(array $values, array $mapped = [], string $purpose = 'email_marketing', ?array $answers = null): self
    {
        $values = CanonicalFields::present($values);
        return new self($values, true, $mapped, $purpose, 'msg_' . bin2hex(random_bytes(16)), PushDetails::sample($values, $purpose, $answers));
    }
}